General Motors had a "culture of cover-up" over a dangerous ignition switch flaw that led to the deaths of 13 people, and there is no justification for CEO Mary Barra to separate herself from decisions made before she took the company's helm a year ago, members of a Senate subcommittee say.

Barra was on Capitol Hill for a second day Wednesday, after a hearing in the House on Tuesday in which lawmakers grilled her over GM's recall of more than 1 million of its small vehicles, including the popular Chevrolet Cobalt, because of the ignition switch problems, reports The Hill.

But while Barra delivered virtually the same responses to the Senate subcommittee that she did in the House, the senators she faced were tougher on her.

GM had "a culture of cover-up that allowed an engineer to lie under oath repeatedly," said Missouri Democratic Sen. Claire McCaskill, who chairs the subcommittee. "We don't know how many people crashed as a result of this cover-up," McCaskill said. "We do know many died."

The automaker has recalled more than 1.6 million cars that have defective switches, which can cause the cars to shut off abruptly or disable their airbags. On Wednesday, families of the 13 people said to be involved in fatal accidents linked to the GM part attended the Senate hearing.

While Barra attempted to separate herself from decisions that were made before she became GM's CEO and the first woman to be placed in charge of a major U.S. automaker, the senators weren't accepting excuses.

"You're new at your job, but you've been at GM for how many years?" Sen. Barbara Boxer, a Califronia Democrat, asked Barra, who has worked for the automaker for 33 years. "You're a really important person to this company. Something is very strange that such a top employee would know nothing."

The ignition switch problem is not a new one. In some cases, the cars involved were more than a decade old, and lawmakers from both parties and from both the House and Senate say GM took too long to notify drivers of the dangers.

When pressed on whether Cobalts are now safe, Barra said GM's testing shows that the vehicles are safe if drivers use only a single car key on their key rings, and she'd let her own son drive one if he only used the single key, reports The Wall Street Journal.

GM is under investigation not only by Congress but by a federal prosecutor and the National Highway Traffic Safety Administration, which regulates U.S. auto safety.

Barra apologized to victims' families, but subcommittee members were not supportive of her explanations.

Sen. Richard Blumenthal, a Connecticut Democrat, told Barra that if she wants to break with GM's old culture she should agree to compensate the families of victims killed before the company's bankruptcy.

Also, Blumenthal noted, GM should warn owners that they should not drive cars with suspected ignition switch issues until they are fixed because they are not safe.

Boxer told her she was disappointed, "woman to woman," by Barra's lack of answers.

"If this is the new GM, it is sorely lacking in leadership," Boxer told her. "You don't know anything about anything," Boxer told her, after earlier in the day mocking her for trying to separate herself from other GM decisions.

"What about 2005? Is that the new GM or the old GM?" Boxer asked. "Yesterday, I did some things that I'm accountable for."

Barra said that as soon as she learned there was a problem, GM "acted without hesitation," revealing the issue and announcing a recall.

"We did so because whatever mistakes were made in the past, we will not shirk from our responsibilities now and in the future," said Barra.

Barra told The Wall Street Journal in a separate interview that GM's senior executives will now be informed of vehicle safety issues when they are first reported, and that they should be expected to expand recalls if necessary.

"The executive team can only expand, they can never make it smaller," Barra said. "I am trying really hard to communicate that we have made great strides to reduce the bureaucracy within GM."

General Motors had a "culture of cover-up" over a dangerous ignition switch flaw that led to the deaths of 13 people, and there is no justification for CEO Mary Barra to separate herself from decisions made before she took the company's helm a year ago, members of a Senate subcommittee say.